# Characterization of the Immunoglobulin Domain of C. elegans SISS-1/EGF

## TL;DR

This study explores how the immunoglobulin domain of a protein in C. elegans affects sleep and signaling.

## Contribution

The study confirms the essential role of the SISS-1 IgD in sleep and tests its impact when added to another EGF.

## Key findings

- The IgD of SISS-1 is critical for its sleep-promoting function in C. elegans.
- Adding the SISS-1 IgD to LIN-3 alters its signaling properties.
- Ectopic expression of SISS-1 supports the functional importance of its IgD.

## Abstract

Immunoglobulin-like domains (IgDs) are widespread among cell surface proteins and participate in cell adhesion and signaling. A subset of Epidermal Growth Factor (EGF) family ligands possess an IgD, with variable impact on EGF signaling.

C. elegans

SISS-1
is an Ig-EGF released by damaged cells that promotes sleep, and its IgD is necessary for this endogenous function. Here we use
SISS-1
ectopic expression to further investigate IgD function, and our data confirm the critical role of the
SISS-1
IgD in sleep. We also examine the impact of adding the
SISS-1
IgD to another

C. elegans

EGF,
LIN-3
.